Combustion device



May 24, 193s. w, W- PECK 2,118,104

COMBUSTION DEVICE Filed Aug. 26, 1935 Patented May 24, 1938 UNITEDSTATES PATENT OFFICE 2 Claims.

'I'his invention relates to imp-rovements in combustion devices and moreparticularly to retorts such as used in furnaces, or boilers, equippedwith automatic solid fuel stokers.

One of the diiculties encountered in the burning of pulverized solidfuel, such as coal, in retorts placed in the fire boxes of furnaces andboilers, wherein both fuel and air are automatically conducted to theretort is the building up of a mushroom formation of coke at the top ofthe fuel bed which reduces the efficiency of the apparatus as acombustion device. These socalled coke mushrooms appear as the result ofincomplete combustion of the coal due to an insufciency of air suppliedto a part of the body of coal in the retort and therefore they generallyappear at the central portion of the coal bed which is farthest awayfrom the tuyre openings.

It is therefore an object of my invention to provide an improved retortfor solid f'uel stokers wherein the formation of coke mushrooms on theburning fuel bed is eliminated.

Another object is to provide an improved retort that is so shaped as tocause the distribution of air admitted thereto into direct contact withthe entire body of coal contained in the retort.

A further object is to provide an improved retort as described whereinrupture or breakage of the perforated tuyre Wall of the retort throughthermal expansion is reduced to a minimum.

A further object is to provide a retort, as described, which is soshaped as to distribute the live coal bed over a relatively large areawithin the fire box of the furnace, or boiler, without materiallyincreasing the fuel capacity of the retort.

Other objects, the advantages and uses of the invention will becomeapparent after reading the following specification and claims, and aftercon- Isideration of the drawing forming a part of the specification,wherein:

Fig. 1 is a diagrammatic side elevation of an automatic coal stokerequipped with my improved retort;

Fig. 2 is a top plan view partially in section illustrating the retortin Fig. 1, and

Fig. 3 is a sectional View along the line III- III of Fig. 2.

I have selected for illustration herein three species of my improvedretort.

With reference to Figs. 1 to 3, the retort is intended for use with anytype of solid fuel stoker such as a pulverized coal stoker illustratedin outline in Fig. 1. Such a stoker may comprise a hopper 2, mechanism,contained within a housing 3, for driving a coal feed screw, indicatedin dotted line at 4, by means of which coal from the hopper 2 isconveyed into the bowl or tuyre ring of the retort through aninterconnecting tube 5.

My improved retort as illustrated in Figs. l to 3 inclusive, comprisestwo parts; a tuyre ring I and a wind box 3, both of which may beconstructed of cast iron. The wind box 8 has formed in conjunctiontherewith a tubular portion 9, adapted to form a continuation of thecoal feed tube 5, and containing the coal feed screw 4. The innermostend of the portion 9 communicates with the bottom'of the retort. At oneside of the tubular passage 9 is a duct Il through which air may beadmitted from a blower, forming a conventional part of the stokermechanism in the 4housing 3, into that portion I4 of the wind boxsurrounding the bottom wall I0 of the retort and the perforated sidewall I2 of the tuyre ring. It is intended in this form of the retortthat the wind box 8 shall rest directly upon some supporting surface, asindicated at I3, and therefore such support forms the bottom wall forthe air chamber I4 surrounding the retort wall at the inner end of theair duct II.

A clean-out passage I6 is provided on the opposite side of the fuelinlet tube 9 which also communicates with the air chamber I4 and isnormally closed by a cap I'I. This passage is employed for the purposeof removing powdered coal from the air chamber, from time to time.

The tuyre ring 1 may be fixed in place upon upstanding wall extensionsI8 of the wind box 8, by means of bolts I9, so that it is not necessaryto remove the retort from the furnace to replace or repair the tuyrering; but instead the ring may be detached from the wind box and liftedupwardly and through the re door 22 of the furnace, thus saving theremoval and replacement of masonry such as required properly to seal theretort in the furnace.

It will be noted that the contour of the retort, as defined by its innerside wall I2, is substantially heart-shaped" with the narrow end inregister with the terminus of the fuel inlet tube 9. This contourprovides a cleavage surface 23 which serves to divide the incomingstream of pulverized coal into two parts forming areas indicated at 24and 25, respectively. The dividing of the coal stream in this mannerserves a twofold purpose: i

(A) There is a mechanical disturbance of the Y tuyre wall I2 may be ofrelatively thin construccoal bed at the cleavage surface 23, which issubstantially at the middle point of the aggregate bed area, thatfunctions to break up any coke formation which may have started to form.

(B) The greatest distance between the midportion of the coal bed and theadjacent slotted tuyre wall is reduced, thus to assure completepenetration of the bed of coals by the incoming air admitted through thetuyre slots 28 in the wall I2. This condition likewise discourages theformation of coke mushrooms because it encourages complete combustion,both under natural and forced draft.

As heretofore stated, both tuyre ring 'I and wind box 8 maybe formed ofcast iron, preferably gray iron, and that wall of the wind box formingthe bottom wall I0 of the retort and tion, thus expediting heatradiation which, iS highly desirable in keeping the Wall cool to prolongthe useful life of the retort.

Another and important feature of my improved retort is the contour andarrangement of the plurality of tuyre slots 28 formed through the tuyrewall I2. vertically spaced groups throughout the entire wall surface,the slots of one group being staggered with respect to the slots of theadjacent groups. This arrangement greatly increases the limit ofelasticity of the tuyre wall under thermal expansion beyond whichrupture or breakage of the wall may take place. Under actual workingconditions I have observed local bulging of the tuyre wall, underVthermal ex-v pansion, to an extent which would have resulted in ruptureor breakage were it not for this staggering of the slots and consequentstaggering of the portions between the slots. Another feature ofthe'retort is the formation of the tuyre slots with their side walls 3Idiverging in the direction of the air chamber. This simple yet highlyeffective arrangement precludes the choking of the tuyre slots by fuelor ash which may pass These slots are arranged inV into the slots fromwithin the retort. Such material having once entered the slot mustnecessarily fall into the air chamber I4 where it may be removed atleisure through the clean-out passageway I 6.

I claim as my invention:

1. A combustion device comprising a cast ferrous` metal retortcomprising an enclosing wall sloping downward and inward, said reto-rtbeing approximately heart-shaped in horizontal contour and having anopening adjacent the bottom thereof at the narrow end thereof foradmitting pulverized coal, whereby coal admitted toV said heart-shapedretort will be divided into two angularly divergent streams, and meansproviding an air chamber surrounding the retort and having an air inletthrough which air under pressure may be admitted to the chamber, thewall of said retort being further formed with a plurality of elongatedtuyre slots therethrough arranged in vertically spaced groups, theslotsy of one group being staggered relative to the slots of theadjacent group.

2. A combustion device comprising a cast ferrous metal retortapproximately heart-shaped in horizontal cross section, said retortcomprising an enclosing wall sloping downward and inward, with the wallat the central portion of the Vretort sloping downward toward the narrowend of the retort to provide a dividing ridge at a point beyond themid-section of the retort, whereby to induce divergence and elevation ofpulverized coal` admitted to the retort through the narrow end thereof,means providing an entrance for pulverized fuel at the narrow end of theretort adjacent the bottom thereof and in Valignment with said dividingridge, and means providing an air chamber surrounding the retort andhaving an aii` inlet opening through which air under pressure may beadmitted, the wall of the retort being provided with a plurality oftuyre slots therethrough. Y

WILLIAM W. PECK.

